There are many circumstances in which it is undesirable for a surgeon to make a relatively large incision in a patient's body in order to perform surgical procedures at internal locations. With wide availability of fiber-optic techniques, surgeons can now avoid making large abdominal incisions by using endoscopic surgical techniques. This typically requires the surgeon to forcibly introduce, under local anesthetic, one or more cannulae through the outer skin into the patient's body. Such cannulae typically have outer diameters in the range 5-10 mm.
As best understood with reference to FIG. 1, a sharp-pointed rod, known as a "trocar", is provided inside the cannula and facilitates forcible intromission of the cannula into the patient's body. The trocar with its point projecting at the front of the cannula is thus used to perforate the outer skin and enables pushing in of the elongate cannula (with the elongate body of the trocar within) through a succession of skin, muscle and fat layers, e.g., for laparoscopic surgery in the abdomen of a patient. Following such an insertion of the trocar and its surrounding cannula, the trocar is removed and the cannula left in place. The surgeon can thereafter insert through the cannula a variety of small bore instrumentation as necessary to perform various surgical functions. It is quite common to employ a number of cannulae suitably placed, as determined by x-ray or ultrasonic scanning of the patient's body, so that the innermost ends of the various cannulae are disposed close to the selected surgical site.
The variety of instruments which may thus be deployed through one or more cannulae include an optic fiber connected to finely-controlled camera equipment to view and externally display the surgical field on a monitor for study by the surgical team, instruments for specifically grasping and/or manipulating tissue, or a multi-function device by which the surgeon can perform cutting and body-fluid coagulating functions simultaneously. The active end portion of such a device may be a laser energy heated element or a laser-energy emitting tip element.
Through endoscopy surgeons can perform very precise surgery by remote control of the surgical tools. The key to success is precisely adjustable placement of the cannulae at suitable locations and in specific orientation with respect to the surgical site, so that instruments may be introduced through the cannulae selectively. Thus, for example, the surgeon most likely will place a cannula which is to be used to obtain a view of the surgical field via fiber optics above the surgical site rather than to a side thereof. As indicated earlier, during a complex surgical procedure the surgical team may remove an instrument from a particular cannula and replace it with another instrument and/or move the removed instrument into another cannula. If this technique is to be practiced, depending on how more than one instrument is to be used, there may be difficulties associated with the location of the available cannulae. This is particularly serious when very precise surgical operations are to be performed and particularly where it is essential to minimize internal trauma to the patient in the course of performing the surgery.
The present invention is intended to afford a surgeon greater latitude and efficiency in precisely performing a variety of surgical functions through one or more cannulae.